In general terms a user interface (UI) includes all aspects of an apparatus or a program, which are used for an interaction with a user. This includes commands and mechanisms, which the user utilizes to control the operation of the apparatus or program and to input data but also an output by the apparatus or program, which can be seen or heard or otherwise perceived by the user.
Especially for consumer electronic apparatuses and computer systems a wide range of user interfaces has been developed and implemented. A very simple and today in many areas outdated user interface requires the user to type textual commands by using a keyboard and produces a single stream of text as output. More comfortable are graphical user interfaces, which use for the output displayed windows, pictures or icons and for the input and control a cursor moved over the display using “up”- and “down”-keys or a pointing device such as a mouse, a trackball or a touch-pad. Even more sophisticated is a voice-controlled user interface based on speech recognition. However, a drawback of these user interfaces is that they are defined and fixed once the respective apparatus has left the factory which means that no extensions or corrections are possible.